The invention concerns an apparatus for the production of mat-like webs from a mixture of granules, in particular, for the manufacture of floor coverings such as a PVC covering.
The apparatus comprises a conveyor belt and a feeder device including a funnel for feeding the mixture of granules. A sizing roll is located adjacent to the outlet of the funnel. The layer of granules deposited on the conveyor belt is then processed into the end product under the effect of pressure and temperature.
An apparatus of this type is known (e.g., see U.S. Pat. No. 2,069,589). In this known apparatus two endless belts are provided, the belts being conducted in a meandering fashion around heating and pressure rolls and receiving between them a layer of granules deposited from a funnel. The floor covering, to be prepared in the form of a web, is made from vulcanizable rubber granules. In order to control the thickness of the layer of rubber granules, a sizing roll is provided adjacent the funnel outlet, along which the granules are passing. A disadvantage may result if the sizing roll has a large diameter, because the rubber granules may be deformed thereunder, especially if a thin layer is being produced. One cause of this problem is that two granules are drawn in while located on top of each other and are thereby deformed. This results in an uneven profile of the end product, particularly when granules of different colors are being fed.
On the other hand, if the sizing roll has a diameter that is too small, the granules are not drawn in uniformly, because due to blocking and bridging, a dam is formed in front of the sizing roll, leading to local voids in the covering. In this case an uneven profile is again created in the product.
It is an object of the invention to design an apparatus of the afore-mentioned type such that the deposited granules form a continuous, uniform layer, without the risk of the local squeezing of granules.